Phys.org April 21, 2021 An abrupt change in the Fermi surface topology, also called Lifshitz transition, can lead to the emergence of fascinating phenomena like colossal magnetoresistance and superconductivity. Controlling the electrons’ arrangement has been a key topic for decades. An international team of researchers (Germany, Sweden, US – research organization) has massively cut down the switching time to only 100 femtoseconds by shooting ultrashort optical laser pulses at a semi-metallic crystal composed of tungsten and tellurium atoms. Shining light on the crystal encourages it to reorganize its internal electronic structure, which also changes the conductivity of the crystal. They […]
Category Archives: Materials science
Discovery could help lengthen lifespan of electronic devices
Science Daily April 9, 2021 Ferroelectric materials are subjected to repeated mechanical and electrical loading, leading to a progressive decrease in their functionality, ultimately resulting in failure. An international team of researchers (Australia, China, USA – Pacific Northwest National Laboratory) observed ferroelectric fatigue as it occurred using in-situ biasing transmission electron microscopy. They discovered that charge accumulation at domain walls is the main reason of the formation of c domains, which are less responsive to the applied electric field. The rapid growth of the frozen c domains leads to the ferroelectric degradation. This finding gives insights into the nature of […]
Scientists discover three liquid phases in aerosol particles
Phys.org April 12, 2021 Aerosol particles fill the atmosphere and play a critical role in air quality. These particles contribute to poor air quality and absorb and reflect solar radiation, affecting the climate system. An international team of researchers (Canada, USA – UC Irvine, Pacific Northwest National Laboratory, Harvard University, Georgia Institute of Technology, Germany) used optical and fluorescence microscopy, to present images that showed the coexistence of two noncrystalline phases for real-world samples as well as for laboratory-generated samples under simulated atmospheric conditions. The results revealed that atmospheric particles can undergo liquid–liquid phase separations. The study focused on particles […]
Scientists develop new approach to predict how liquids freeze
Phys.org March 18, 2021 Denser phases and the complexity of the freezing liquids into solids are a challenge for computational modelling. Researchers in the UK developed novel computational approaches to study wax which has multiple frozen arrangements. Using their method, they were able to predict its melting point within 2°C of the experimental value. Like waxes, oils such as diesel fuel can also freeze at many stages and exhibit different solid properties. Therefore, methods to predict the molecular and atomic intricacies of liquid transitions to different types of ‘solid’ oils could have several potential real-world applications, from helping better predict […]
New research could boost a solar-powered fuel made by splitting water
Science Daily March 10, 2021 Altering crystal facets exposed on the surface of photoelectrodes used for solar fuel production has been a major strategy for optimizing their properties. There are numerous ways to terminate the surface even for the same facet, which can considerably alter the photoelectrode properties. A team of researchers in the US (University of Wisconsin, University of Chicago, Brookhaven National Laboratory, Stony Brook University, Argonne National Laboratory) investigated using tightly integrated experimental and computational investigations of epitaxial BiVO4 photoelectrodes with vanadium- and bismuth-rich (010) facets. The study demonstrated that even for the same facet the surface Bi:V […]
Virtually unlimited solar cell experiments
EurekAlert March1, 2021 Researchers in Japan used machine learning to screen hundreds of thousands of donor: acceptor pairs based on an algorithm trained with data from previously published experimental studies. Trying all possible combinations of 382 donor molecules and 526 acceptor molecules resulted in 200,932 pairs that were virtually tested by predicting their energy conversion efficiency. Basing the construction of our machine learning model on an experimental dataset drastically improved the prediction accuracy. To verify this method, one of the polymers predicted to have high efficiency was synthesized in the lab and tested. Its properties were found to conform with […]
Jumping frost crystals: Lab works toward electrostatic de-icing
Phys.org February 24, 2021 Charge separation in frost has been studied in the past, but the effect has never been exploited to remove the frost from its surface. A team of researchers in the US (Virginia Tech, UC Santa Barbara) exploited the spontaneous electrification of ice to reveal a surprising phenomenon of jumping frost dendrites. They observed frost dendrites breaking off from mother dendrites and/or the substrate to jump out-of-plane toward an opposing polar liquid. They developed analytical and numerical models to estimate the attractive force between the frost dendrites and liquid and found it to be in good agreement […]
Quickly identify high-performance multi-element catalysts
Eurekalert February 17, 2021 Many electrochemical reactions go through several steps. Each should be optimized on a catalyst surface if possible, but different requirements apply to each step. With the example of the oxygen reduction reaction, an international team of researchers (Denmark, Germany) showed that for high entropy alloys comprising five or more principal elements, by utilizing a data‐driven discovery cycle, the multidimensionality challenge raised by this catalyst class can be mastered. Iteratively refined computational models predict activity trends around which continuous composition‐spread thin‐film libraries are synthesised. High throughput characterisation datasets are then used as input for refinement of the […]
Defects may help scientists understand the exotic physics of topology
Science Daily January 22, 2021 Researchers at the University of Illinois engineered metamaterials to include defects to show that defects and structural deformations can provide insights into a real material’s hidden topological features. They experimentally demonstrated that disclination defects can robustly trap fractional charges in topological crystalline insulators (TCI) metamaterials, and the trapped charge can indicate non-trivial, higher-order crystalline topology even in the absence of any spectral signatures. They uncovered a connection between the trapped charge and the existence of topological bound states localized at these defects. By testing the robustness of these topological features when the protective crystalline symmetry […]
Experimental evidence of an intermediate state of matter between a crystal and a liquid
EurekAlert January 19, 2021 Researchers in Russia present a detailed analysis of their experimental study, which shows clear evidence of a two-stage melting process of a quasi-two-dimensional dusty plasma system in a high-frequency gas discharge. They accurately calculated global parameters of the orientational and translational order, as well as their susceptibilities to determine two critical points, related to “solid-to-hexatic” and “hexatic-to-liquid” phase transitions. The nature of the emerging defects and changes in their mutual concentration, in addition to the estimate of core energy of free dislocations also counts in favor of the formation of an intermediate hexatic phase. These results […]